feat: add postgres result store

[serendipty01]

Added for ease in local development

Need to change below env to enable this
OSPREY_EXECUTION_RESULT_STORAGE_BACKEND=postgres

Note:
I haven't tested with druid setup
Also, I'm not deeply familiar with Python or this codebase, so let me know anything that needs to be changed or improved.

Tested with Hailey's fork

[ayubun]

i like the pr, but i don't love some of the naming in it. i think we should change all of the existing names (perhaps in a different pr)

@EXBreder @haileyok maybe we should move discord to this store for localdev, since we already have a postgres locally for other elements of the ui & the bigtable simulator is annoying to use 😆

[ayubun]

i know you're just following conventions that have existed before you, but i'm not in love with this naming scheme. perhaps for a different pr, it could be renamed to something more descriptive:

Suggested change

	class StoredExecutionResultPostgres(ExecutionResultStore):
	class PostgresExecutionResultStore(BaseExecutionResultStore):

the term StoredExecutionResult implies that the class is a pydantic object / dataclass, but this is just an interface for the result store

[haileyok]

nice! im curious since you were testing w/ my fork and atproto data, were you handling the full firehose throughput? im curious what the perf on inserts was for you!

i pushed a changelog entry too for you, we need to put that in the pr template 😅